Excessive reduction of coal combustion might lead to a spurt of demand for scarce natural gas, so coal-to-gas projects should be implemented cautiously and rationally, experts warned.

"Coal consumption has always been blamed as the major culprit of the notorious air pollution, but the reason lies in the utilization technology rather than the coal itself," said Cao Xianghong, a CPPCC member and director of the National Petroleum Products and Lubricants Standardization Technical Committee for more than 10 years.

"Advanced technology enables clean coal to produce very little sulfur content in the emission, and the pollutant discharge of clean coal is on par with natural gas," he said.